Potamogeton foliosus Raf.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Stems to 7 dm, usually freely branched, slightly compressed, to 1 mm wide, usually without nodal glands; rhizome slender and elongate; lvs all submersed, linear, 1.5–8 × 0.5–2 mm, mostly acute or apiculate, 1–3(5)-veined, with 0–2 rows of lacunar cells flanking the midvein; stipulate sheaths axillary, free, greenish to brown, 0.5–2 cm, tubular, with connate margins, delicate to slightly fibrous; winter-buds uncommon, 1–2 cm, the inner lvs rolled into hard, fusiform structure; peduncles axillary, usually clavate, recurved, 5–15 mm, seldom longer; spikes mostly capitate, 2–7 mm, with 1 or 2 whorls of fls; body of the fr 1.5–2.7 mm, with rounded to often concave sides and an undulate, wing-like dorsal keel, the beak 0.2–0.6 mm; 2n=28. Streams and ponds; N.S. and Que. to Alas., s. to W.I. and C. Amer. Ours is the widespread var. foliosus.